Auto-fluorescence (AF) is the natural emission of light by biological structures such as mitochondria and lysozomes when they have absorbed light. In some medical applications, AF can be used to illuminate structures of interest, or as a diagnostic indicator. For example, cellular AF can be used as an indicator of cytotoxicity.
Photodynamic Diagnosis (PDD) is another medical application of fluorescence. In PDD, malignant tissue can be differentiated from benign tissue by administering a suitable fluorescence marker. Typically the marker is selected such that it is preferentially absorbed by tumors. Under appropriate diagnostic lighting, the marker can be made to fluoresce, helping to define the borders of the tumor for identification and diagnosis or for removal by a surgeon, for example. In some applications, diagnostic light of varying wavelengths can be used to differentiate tissue without administering a drug.
Photodynamic Therapy (PDT) is conducted similarly to PDD, except that the drug which is administered and preferentially absorbed by malignant tissue is used in subsequent destruction of that tissue. Typically, PDT applications involve the use of a photosensitizer, a light source, and tissue oxygen. The wavelength of the light source is tuned to excite the photosensitizer in order to produce reactive oxygen species. The combination of these elements leads to the destruction of any tissues which have selectively taken up the photosensitizer and are locally exposed to light from the light source.
Prior art systems for these applications are known. One example is the Karl Storz D-Light C PDD System. This system incorporates an endoscope, such as a cystoscope used in bladder and urethra examinations. Diagnostic light is supplied to the endoscope from a separate and remote external light source using a light guide, which may be a quartz light guide or a fluid light cable, for instance. The closed end of the light cable is inserted into a socket on the light source. The open end of the light cable is connected to a light post that is a part of the endoscope.
As is typical for known systems, the light source incorporates a lamp to generate the diagnostic light. In this case, a 300 W Cermax® Lamp is used. The light source is sizeable, measuring 300 mm×164 mm×320 mm, and weighting approximately 11 kg. The lamp is a xenon arc lamp generating incoherent light, which must be replaced after an operating time of 400 hours. The light source is typically housed in a tower, which is a rack mounting system.
Another known system is disclosed in U.S. Pat. No. 6,640,131 to Irion et al., assigned to Karl Storz GmbH & Co., the content of which is incorporated herein in its entirety.
Such discrete component systems are complicated, delicate, cumbersome, and require frequent maintenance of the light source.
Other known approaches to PDT, PDD or AF endoscopy have incorporated light emitting diodes. However, these applications have used diodes at the distal end of the endoscope. Furthermore, these systems have supported limited additional functionality.
U.S. Pat. No. 7,351,242 to Neuberger et al. discloses an endoscope for PDT having low wattage diodes at the distal end. However, Neuberger et al. does not teach the use of a diode laser incorporated into the proximal end for PDT/PDD applications, does not teach synchronous video and diode pulsing for simultaneous readout of multiple diagnostic modes or treatment, and teaches away from the use of a non-distally located light source.
U.S. Pat. No. 5,468,238 to Mersch discloses an endoscope having a diode laser at the distal end for cutting or coagulating tissue. However, Mersch does not teach the use of a diode laser incorporated into the proximal end for PDT/PDD applications, does not teach synchronous video and diode pulsing for simultaneous readout of multiple diagnostic modes or treatment, and teaches away from the use of a non-distally located light source.
US Patent Publication No. 2008/0114419 to Crowley discloses a miniature light device at the distal end of an interventional device, including distally located laser diodes used for PDT. However, Crowley does not teach the use of a diode laser incorporated into the proximal end for PDT/PDD applications, does not teach synchronous video and diode pulsing for simultaneous readout of multiple diagnostic modes or treatment, and teaches away from the use of a non-distally located light source.
Other known approaches to endoscopic illumination have incorporated light emitting diodes at the proximal end of the endoscope. However, these applications have not been designed for use in PDT, PDD or AF applications, and systems have supported limited additional functionality.
U.S. Pat. No. 6,730,019 to Irion, assigned to Karl Storz GmbH & Co., discloses an endoscope for multi-color illumination having multiple light emitting diodes at the proximal end, emitting visible light of different colors which is additively mixed to provide faithful full color imaging. The diodes are used for color modulation. However, Irion does not teach the use of non-visible wavelength diodes, PDT applications, or synchronous video and diode pulsing for simultaneous readout of multiple diagnostic modes of treatment.
US Patent Publication No. 2011/0245603 to Brannon discloses a detachable external visible laser source which can be attached to the proximal end of an endoscope for use as a sighting device for aiming the endoscope. However, Brannon not teach the use of multiple different wavelength laser diodes, non-visible wavelength diodes, PDT, PDD or AF applications, video recording, or synchronous video and diode pulsing for simultaneous readout of multiple diagnostic modes or treatments.
It is therefore desired to provide a device which addresses these deficiencies.